Thomas Vermaelen has warned Arsenal they must put Robin van Persie’s departure behind them and focus on launching a sustained assault on the Premier League.

Robin van Persie is on the verge of finalising a move to Old Trafford (Picture: Action Images)

The former Gunners skipper has travelled to Manchester to finalise a £24million switch to Old Trafford, having earlier in the summer announced he would not be signing a new deal in north London.Arsenal were prepared to make their key striker the highest paid player in the club’s history, but sanctioned his exit when it became clear the Dutchman wanted to move.Belgium defender Vermaelen is now likely to inherit the captain’s armband, and, ahead of Saturday’s kick-off against Sunderland at the Emirates Stadium, said: ‘He was fantastic for us in the last year, scored lots of goals and I am disappointed he is going, but we have to focus on the next season with Arsenal.‘We have to fight and I am confident we have a squad to win something. Robin is leaving and we have to move on.’Gunners boss Arsene Wenger insisted the club were left with ‘no choice’ but to allow Van Persie to leave.However, he believes the summer additions of strikers Olivier Giroud and Lukas Podolski will offset the loss to the squad.‘It is never great to lose players of that quality, but he only had a year contract so we do not have a choice,’ said Wenger.‘Honestly, I’d have preferred to sell him abroad, to Paris Saint-Germain, for example, over Manchester United.‘They have the advantage of having played against him and knowing his great class.‘He’s truly an exceptional player in every sense of the word.’